Infectious Cellulitis: Causes, Symptoms, Complications, Diagnosis, Treatment and Prevention

It is a serious infection that extends under the skin and affects soft tissues, such as skin and fat.

Bacteria are the most common cause, but very occasionally a fungus may be responsible.

Cellulite is not contagious, but it can affect anyone with broken skin or damaged tissue. Cellulitis infections occur most often in the legs, arms or face.

Facial infections are found mainly in babies and the elderly. In children, approximately 1 in 12 cases of facial cellulitis causes meningitis .

Cellulite occurs in different ways. Periorbital cellulitis occurs around the eye sockets.

The erysipelas produces red, strong and bright spots on the skin and is caused by Streptococcus bacteria. Necrotizing fasciitis is an infection that occurs under the skin.


Cellulite usually begins with a cut or tear in the skin.

Many species of bacteria inhabit the surface of the skin and can thrive under the skin if the barrier breaks to let them pass.

Bacteria can infect burns and bruises, as well as cuts and scratches, puncture wounds and dermatitis. Other traumas that can lead to infection include:

  • The surgeries.
  • The dental treatments.
  • The bites of animals or humans.

There are several bacteria that can cause cellulitis, among them Streptococcus and Staphylococcus are the two most common species.

The actual type of bacteria that causes the infection depends on the nature of the exposure, such as infections resulting from a cut, the bite of a cat or dog, or swimming with broken skin.

Cellulite can sometimes start even on the skin that has not been broken.

This usually only happens in people with weakened immune systems .

People with diabetes, people with alcoholism habits, people who take corticosteroids and others with compromised immune systems have a much higher risk of cellulitis and tend to worsen infections.

Necrotizing cellulitis (or necrotizing fasciitis ) is a rare but serious form of cellulitis.

There are two kinds; the first is due to a very aggressive strain of group A streptococcus and can start anywhere on the skin.

The second is due to a polymicrobial infection of different bacteria that often begins just ahead of the anus after surgery or rectal abscesses.

The necrotizing cellulitis begins as an extremely painful red swelling that soon becomes purple and then black as the skin and tissues become necrotic.

However, the risk of getting necrotizing cellulitis is extremely small.

Symptoms and complications

Uncomplicated cellulitis begins with a small area of ​​skin that is red, shiny, painful, and warm to the touch, usually around a cut.

It often starts in the lower part of the leg, but the arms, hands, feet and groin are other of the most likely areas.

Some types of bacteria can enter the lymphatic system , the network of lymphatic vessels and nodes that carry cells that fight diseases and waste substances through the body.

If this happens, the infection can travel and spread to other parts of the body. Another type of cellulitis is erysipelas .

The inflamed skin in the erysipelas is not smooth but raised, often completely separated from the lower layer by a pocket of gas created by the bacteria. There is often a fever one or two days before the rash.

The most serious complications of cellulitis are meningitis and sepsis, infections that enter the bloodstream ( bacteremia ).

Meningitis can occur if the bacteria enters the central nervous system as the brain or spinal cord . The most likely route is through the eye socket.

Cellulitis around an eyelid is called preseptal cellulitis. It causes a rash that can be painful or itchy.

If the bacteria is behind the seal where the eye meets the alveolus, the condition is called orbital cellulitis. This is a medical emergency that causes symptoms of fever and vision problems. It requires immediate treatment to prevent meningitis or damage to the eyes.

If the infection enters the lymphatic system or into the bloodstream, red lines can be seen under the skin before the main lesions appear.

This can cause symptoms such as fever, sweating and nausea.


The doctor can usually recognize cellulite from the appearance of the skin.

Unless there is pus or an open wound, the responsible organism can be difficult to identify.

The exact strain of the bacteria is not usually important, since the typical antibiotics are “broad spectrum” and fight most of the bacteria that cause cellulite infections.

Treatment and prevention

Various types of antibiotics are used to treat cellulite among them oral antibiotics such as amoxicillin or cefalexin .

The type of antibiotic prescribed will depend on the cause, the severity of the infection and the presence of other medical conditions.

Uncomplicated cellulite should begin to disappear in a few days.

It is important to complete the prescribed treatment with the dose and time indicated, even if the symptoms disappear. Analgesics such as acetaminophen or dipyrone may also be prescribed .

When the antibiotic treatment begins, the doctor may indicate that the movement of the affected area is restricted and that it rests until the infection begins to decrease and the fever decreases.

Once the infection begins to improve, normal activities can resume.

Elevating the affected area so that it is at a level higher than the heart will reduce swelling and pain.

Warm compresses increase blood flow and can help fight infections.

Recently, more cases of cellulitis and other skin infections have been linked to methicillin-resistant Staphylococcus aureus.

This bacterium requires specific types of antibiotics for its treatment.

Antibiotics alone do not work fast enough to stop necrotizing cellulitis, so infected tissues must be eliminated.

Sometimes, amputation is the only way to prevent the disease from invading the rest of the body.